Reflective Safety Wear and Robotic Instruments

I use a Topcon GPT 8005A robot, and I have never had any issues that I have noticed, and I wear a vest almost every day in the field. It is an older robot, though.

I've used early Topcon robots, then Leica and now a Trimble S series robot and have had all of them grab my vest (reflective strips) at some time or another. I've grown a custom to turning my vest inside out when I get the robot out.

Any robot with passive tracking will lock on any reflective surface. Active tracking will stay locked on the leds of the prism, but sometimes will lock on a reflection of the leds in glass. Had that happen a couple times around buildings.

Trimble S-Series with the MT1000 will not track anything but the MT1000 and on the channel specified... but as noted above I've heard of one or two instances of it tracking the reflection of the diodes.

Great question.

I can only offer the following observations.

Had a Leica 1203 track and shoot the reflection of the 360 prism off a glass window I was standing in front of. Didn't realize it until during the drafting of the topo.

Had a Topcon 800 series robot pick up and shoot the distance to a retroreflective highway sign that was about 30' behind me. Never lost lock on the prism, but apparently the retroreflective sign panel picked up and bounced back some or all of the distance measurement signal. Again, this wasn't apparent until back at the office looking at the topo data.

On several occurance I've had a Topcon QS pick up passing vehicles during measurements. Strange thing about these measurements was that the distances were accurate to the prism shot, but the angles were representative of the path of the passing vehicle. Makes me think the measurement mode has some delay in sequence of the distance, V and H angles.

Yup I just turn my reflective safety vest inside out when in robotic mode. I have learned to zip it up from the inside.

I guess I have not had any problems with my robot because I almost always run a 6.5' rod to keep the prism above my head so I do not block the line of sight.

[sarcasm]I would be happy if it tracked anything on or near me at times.[/sarcasm]

Yes, the Leica TCRP-1203 robot will bounce infrared EDM off your reflective vest within 35-50 feet especially if your EDM intensity is set to high. If you're in ATR (auto) or LOCK mode, the clue is usually that it reports trouble holding lock. I have never had it actually track the vest.

Likewise, standing in front of some plate glass windows, the EDM might bounce off the glass if it's looking straight in. The older TCRA-1100 total stations were prone to tracking the tail lights of Mercedes sedans, but I haven't had that problem with the newer robots.

Regards,
Mike

The original GDM4400 units used to suffer badly from this; the later ones less so. Most modern machines don't seem to have too much problem. If they are on lock then they are continually checking for the pulsed LED and while they will follow a reflective surface for a short time they stop quickly if no LED is found.

There was one advantage of the original units in that in heavy woodland they could follow bits of your hi-vis easier than the target. When you wanted a shot then waving the target slowly enabled them to pick up the LED and display a tracked distance. They would then hold the target while you positioned.

The flashing LED seems to have a superimposed pattern on it, so while it might appear to flash at X times a minute, there is an occasional extra or missing pulse. I assume this is how it knows it is looking at its own target, rather than a random external source which just happens to be flashing at about the same frequency.

I wear the vest every time I go out, and I have never had a problem. Like Jimmy, I keep the prism above my head to avoid blocking the line of sight. The only issue with the higher rod heights is that you have be even more careful to ensure that your prism pole bubble is calibrated and that the pole is truly plumb.

I do recall having issues a while ago with the Leica 1200 series tracking the reflection of the prism in a puddle and also the same thing with a window across a lagoon.

I've used Geodometer 400, Trimble 5600, and Sokkia SX all in construction work. Never have a problem with the Geodometer/Trimble units locking onto anything other than the prism. I'm assuming it was due to the LEDs because that's what they track. The Sokkia robot tracked the prism and I had many problems with it locking onto tail lights, mirrors, and anything that reflects light.

I was staking a parking lot and I was having problem with a particular setup where the gun was pointing in a certain direction. There was nothing noticeably reflective and couldn't figure out what was the problem. After much trouble shooting with Carlson (Carlson Surveyor plus data collector), salesman and Sokkia I figured out what was going on. There was a martial arts studio across the street about 600 feet away from the site. The gun was getting signals from the mirrors on the back of the studio. The signal went through a chain link fence, traffic, store front windows, and then to the mirrors and back. I was truly impressed that the signal was good enough to even register a shot. Had to move the gun to look away from the studio and everything was perfect.

Yes. Like a toddler those instruments love bright shiny objects.

The crew came back with one last fall. Half the Edge of Pavement shots were on top of the backsight. The I-Man learned to keep an eye on the autotrack.

Yes my VX will track my vest, but only if it loses lock on the prism and it starts the search.

It's a massive PITA! I have the active track thingy but don't use it so most of the frustration is my fault.

That is the difference between a passive and active target. In a target hostile environment you can switch to an on demand measurement mode which may help avoid an inadvertent measurement.